Generally, typical buildings use double glazed windows in order to reduce heat loss through windows and doors. Such a double glazed window generally includes a vacuum space between two glass plates constituting the double glazed window in order to minimize heat loss.
The double glazed window effectively reduces heat loss, but the light transmittance thereof cannot be adjusted, and thus a user generally uses curtains, blinds or sun blocking films in order to adjust the amount of incident light entering an indoor space. Further, since the color and light transmittance of the double glazed window cannot be changed once it is installed, an additional object is needed. Still further, in the case in which an advertisement material is attached to glass plates of the double glazed window for advertising purposes, since windows and doors in buildings generally remain as they are for their entire life span, the design of the windows remains unchanged for the entire lifespan thereof. That is, the windows or doors of the buildings are monotonous.
Further, in the case in which there is an apparatus having a blind or a film interposed between glass plates, no matter how transparent the film is, the transparency of the apparatus is inferior to an apparatus not having a film.
Still further, in the case in which a film is completely wound onto a winding roller, the film combined with the winding roller can be damaged by the strong shock that occurs when the film is completely wound thereon, and the film may become wrinkled as time passes.